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> The highest key waveform looks very different.</div>
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That looks to me like the phase of the modulating frequency is different wrt to carrier compared with the other notes. Don't know if this is a DX-7 thing or just a random phase of the moon thing.<br>
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<div id="divRplyFwdMsg" dir="ltr"><font style="font-size:11pt" face="Calibri, sans-serif" color="#000000"><b>From:</b> Synth-diy <synth-diy-bounces@synth-diy.org> on behalf of Ingo Debus via Synth-diy <synth-diy@synth-diy.org><br>
<b>Sent:</b> 27 November 2022 13:44<br>
<b>To:</b> synth-diy mailing list <synth-diy@synth-diy.org><br>
<b>Subject:</b> [sdiy] Frequency modulation vs Phase mod, was: Buchla 295 10-band comb filter topology</font>
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So here we go. I measured the output of my DX7, for all six C keys of its keyboard. It was set to Init Voice, with the following modifications:
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<div class="" style="margin:0px; font-stretch:normal; line-height:normal">Algorithm 1</div>
<div class="" style="margin:0px; font-stretch:normal; line-height:normal">Op1 Output Level 99</div>
<div class="" style="margin:0px; font-stretch:normal; line-height:normal">Op2 Output Level 99</div>
<div class="" style="margin:0px; font-stretch:normal; line-height:normal">Op3…Op6 Output Level 0</div>
<div class="" style="margin:0px; font-stretch:normal; line-height:normal">Keyboard Scaling all 0</div>
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<div class="" style="margin:0px; font-stretch:normal; line-height:normal">We see that the waveforms of all keys except the highest key look similar, but not exactly the same. The highest key waveform looks very different. Maybe this is just a lowpass filter
effect of the DX7 (certainly not of the scope, this is a 60 MHz scope). The frequency of the highest key is about 2 kHz.</div>
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<div class="" style="margin:0px; font-stretch:normal; line-height:normal">If anyone wants me to measure something else, let me know!</div>
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<div class="" style="margin:0px; font-stretch:normal; line-height:normal">Ingo</div>
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